The present invention relates to the process of thermally treating starch in the presence of an low molecular weight carbohydrate to improve the rate of thermal inhibition of the starch. Under certain processing conditions, the resultant starch/low molecular weight carbohydrate blend has improved cold storage stability.
Numerous starch products prepared using a variety of processes are known in the art. These include starches which are prepared by thermal inhibition. For example, U.S. Pat. No. 5,725,676 discloses thermally inhibited starches and flours and European Patent Application Publication No. 0 735 827 discloses their use in food products.
Thermal inhibition provides starch which meets consumer demands for foods as they are not chemically modified, but still have the same functional properties as chemically modified foods. These properties include excellent tolerance to processing variables such as heat, shear, and pH extremes; smooth texture; and viscosity stability throughout the processing operation and normal shelf life of the food.
Aqueous dispersions of cross-linked (chemically inhibited) starch are often used under conditions which involve prolonged storage at relatively low temperature and/or exposure, at times, to repeated freezing and thawing cycles. For example, starch dispersions are used in numerous food products such as canned and frozen foods, particularly fruit preps, pies, soups, and the like. In the case of canned food products, these are often stored in warehouses which have no heating facilities and may therefore be at very low temperatures for prolonged periods and may freeze during shipping. Frozen foods are also subject to long term storage at very low temperatures as well as freezing and thawing during distribution and consumer storage. Under such circumstances involving exposure to low temperature, there is typically a distinct loss in the hydrating power of the starch which is present in such food products, thereby resulting in syneresis, an extrusion of liquid, together with a marked deterioration in the texture and clarity of the food product. While sols of waxy maize starch are superior in stability to those of regular corn starch, even they are prone to intermolecular association during storage at or near freezing temperature.
Surprisingly, it has now been discovered that the presence of low molecular weight carbohydrate improves the rate of thermal inhibition of starches and, under certain conditions, result in starch/low molecular weight carbohydrate blends with improved cold storage stability.